1//===- lib/MC/MCELFStreamer.cpp - ELF Object Output -----------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file assembles .s files and emits ELF .o object files.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/MC/MCELFStreamer.h"
15#include "llvm/ADT/STLExtras.h"
16#include "llvm/ADT/SmallPtrSet.h"
17#include "llvm/MC/MCAsmBackend.h"
18#include "llvm/MC/MCAsmLayout.h"
19#include "llvm/MC/MCAsmInfo.h"
20#include "llvm/MC/MCAssembler.h"
21#include "llvm/MC/MCCodeEmitter.h"
22#include "llvm/MC/MCContext.h"
23#include "llvm/MC/MCExpr.h"
24#include "llvm/MC/MCInst.h"
25#include "llvm/MC/MCObjectFileInfo.h"
26#include "llvm/MC/MCObjectStreamer.h"
27#include "llvm/MC/MCObjectWriter.h"
28#include "llvm/MC/MCSection.h"
29#include "llvm/MC/MCSectionELF.h"
30#include "llvm/MC/MCSymbolELF.h"
31#include "llvm/MC/MCSymbol.h"
32#include "llvm/MC/MCValue.h"
33#include "llvm/Support/Debug.h"
34#include "llvm/Support/ELF.h"
35#include "llvm/Support/ErrorHandling.h"
36#include "llvm/Support/TargetRegistry.h"
37#include "llvm/Support/raw_ostream.h"
38
39using namespace llvm;
40
41bool MCELFStreamer::isBundleLocked() const {
42  return getCurrentSectionOnly()->isBundleLocked();
43}
44
45MCELFStreamer::~MCELFStreamer() {
46}
47
48void MCELFStreamer::mergeFragment(MCDataFragment *DF,
49                                  MCDataFragment *EF) {
50  MCAssembler &Assembler = getAssembler();
51
52  if (Assembler.isBundlingEnabled() && Assembler.getRelaxAll()) {
53    uint64_t FSize = EF->getContents().size();
54
55    if (FSize > Assembler.getBundleAlignSize())
56      report_fatal_error("Fragment can't be larger than a bundle size");
57
58    uint64_t RequiredBundlePadding = computeBundlePadding(
59        Assembler, EF, DF->getContents().size(), FSize);
60
61    if (RequiredBundlePadding > UINT8_MAX)
62      report_fatal_error("Padding cannot exceed 255 bytes");
63
64    if (RequiredBundlePadding > 0) {
65      SmallString<256> Code;
66      raw_svector_ostream VecOS(Code);
67      MCObjectWriter *OW = Assembler.getBackend().createObjectWriter(VecOS);
68
69      EF->setBundlePadding(static_cast<uint8_t>(RequiredBundlePadding));
70
71      Assembler.writeFragmentPadding(*EF, FSize, OW);
72      delete OW;
73
74      DF->getContents().append(Code.begin(), Code.end());
75    }
76  }
77
78  flushPendingLabels(DF, DF->getContents().size());
79
80  for (unsigned i = 0, e = EF->getFixups().size(); i != e; ++i) {
81    EF->getFixups()[i].setOffset(EF->getFixups()[i].getOffset() +
82                                 DF->getContents().size());
83    DF->getFixups().push_back(EF->getFixups()[i]);
84  }
85  DF->setHasInstructions(true);
86  DF->getContents().append(EF->getContents().begin(), EF->getContents().end());
87}
88
89void MCELFStreamer::InitSections(bool NoExecStack) {
90  MCContext &Ctx = getContext();
91  SwitchSection(Ctx.getObjectFileInfo()->getTextSection());
92  EmitCodeAlignment(4);
93
94  if (NoExecStack)
95    SwitchSection(Ctx.getAsmInfo()->getNonexecutableStackSection(Ctx));
96}
97
98void MCELFStreamer::EmitLabel(MCSymbol *S) {
99  auto *Symbol = cast<MCSymbolELF>(S);
100  assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
101
102  MCObjectStreamer::EmitLabel(Symbol);
103
104  const MCSectionELF &Section =
105      static_cast<const MCSectionELF &>(*getCurrentSectionOnly());
106  if (Section.getFlags() & ELF::SHF_TLS)
107    Symbol->setType(ELF::STT_TLS);
108}
109
110void MCELFStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
111  // Let the target do whatever target specific stuff it needs to do.
112  getAssembler().getBackend().handleAssemblerFlag(Flag);
113  // Do any generic stuff we need to do.
114  switch (Flag) {
115  case MCAF_SyntaxUnified: return; // no-op here.
116  case MCAF_Code16: return; // Change parsing mode; no-op here.
117  case MCAF_Code32: return; // Change parsing mode; no-op here.
118  case MCAF_Code64: return; // Change parsing mode; no-op here.
119  case MCAF_SubsectionsViaSymbols:
120    getAssembler().setSubsectionsViaSymbols(true);
121    return;
122  }
123
124  llvm_unreachable("invalid assembler flag!");
125}
126
127// If bundle alignment is used and there are any instructions in the section, it
128// needs to be aligned to at least the bundle size.
129static void setSectionAlignmentForBundling(const MCAssembler &Assembler,
130                                           MCSection *Section) {
131  if (Section && Assembler.isBundlingEnabled() && Section->hasInstructions() &&
132      Section->getAlignment() < Assembler.getBundleAlignSize())
133    Section->setAlignment(Assembler.getBundleAlignSize());
134}
135
136void MCELFStreamer::ChangeSection(MCSection *Section,
137                                  const MCExpr *Subsection) {
138  MCSection *CurSection = getCurrentSectionOnly();
139  if (CurSection && isBundleLocked())
140    report_fatal_error("Unterminated .bundle_lock when changing a section");
141
142  MCAssembler &Asm = getAssembler();
143  // Ensure the previous section gets aligned if necessary.
144  setSectionAlignmentForBundling(Asm, CurSection);
145  auto *SectionELF = static_cast<const MCSectionELF *>(Section);
146  const MCSymbol *Grp = SectionELF->getGroup();
147  if (Grp)
148    Asm.registerSymbol(*Grp);
149
150  this->MCObjectStreamer::ChangeSection(Section, Subsection);
151  MCContext &Ctx = getContext();
152  auto *Begin = cast_or_null<MCSymbolELF>(Section->getBeginSymbol());
153  if (!Begin) {
154    Begin = Ctx.getOrCreateSectionSymbol(*SectionELF);
155    Section->setBeginSymbol(Begin);
156  }
157  if (Begin->isUndefined()) {
158    Asm.registerSymbol(*Begin);
159    Begin->setType(ELF::STT_SECTION);
160  }
161}
162
163void MCELFStreamer::EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) {
164  getAssembler().registerSymbol(*Symbol);
165  const MCExpr *Value = MCSymbolRefExpr::create(
166      Symbol, MCSymbolRefExpr::VK_WEAKREF, getContext());
167  Alias->setVariableValue(Value);
168}
169
170// When GNU as encounters more than one .type declaration for an object it seems
171// to use a mechanism similar to the one below to decide which type is actually
172// used in the object file.  The greater of T1 and T2 is selected based on the
173// following ordering:
174//  STT_NOTYPE < STT_OBJECT < STT_FUNC < STT_GNU_IFUNC < STT_TLS < anything else
175// If neither T1 < T2 nor T2 < T1 according to this ordering, use T2 (the user
176// provided type).
177static unsigned CombineSymbolTypes(unsigned T1, unsigned T2) {
178  for (unsigned Type : {ELF::STT_NOTYPE, ELF::STT_OBJECT, ELF::STT_FUNC,
179                        ELF::STT_GNU_IFUNC, ELF::STT_TLS}) {
180    if (T1 == Type)
181      return T2;
182    if (T2 == Type)
183      return T1;
184  }
185
186  return T2;
187}
188
189bool MCELFStreamer::EmitSymbolAttribute(MCSymbol *S, MCSymbolAttr Attribute) {
190  auto *Symbol = cast<MCSymbolELF>(S);
191  // Indirect symbols are handled differently, to match how 'as' handles
192  // them. This makes writing matching .o files easier.
193  if (Attribute == MCSA_IndirectSymbol) {
194    // Note that we intentionally cannot use the symbol data here; this is
195    // important for matching the string table that 'as' generates.
196    IndirectSymbolData ISD;
197    ISD.Symbol = Symbol;
198    ISD.Section = getCurrentSectionOnly();
199    getAssembler().getIndirectSymbols().push_back(ISD);
200    return true;
201  }
202
203  // Adding a symbol attribute always introduces the symbol, note that an
204  // important side effect of calling registerSymbol here is to register
205  // the symbol with the assembler.
206  getAssembler().registerSymbol(*Symbol);
207
208  // The implementation of symbol attributes is designed to match 'as', but it
209  // leaves much to desired. It doesn't really make sense to arbitrarily add and
210  // remove flags, but 'as' allows this (in particular, see .desc).
211  //
212  // In the future it might be worth trying to make these operations more well
213  // defined.
214  switch (Attribute) {
215  case MCSA_LazyReference:
216  case MCSA_Reference:
217  case MCSA_SymbolResolver:
218  case MCSA_PrivateExtern:
219  case MCSA_WeakDefinition:
220  case MCSA_WeakDefAutoPrivate:
221  case MCSA_Invalid:
222  case MCSA_IndirectSymbol:
223    return false;
224
225  case MCSA_NoDeadStrip:
226    // Ignore for now.
227    break;
228
229  case MCSA_ELF_TypeGnuUniqueObject:
230    Symbol->setType(CombineSymbolTypes(Symbol->getType(), ELF::STT_OBJECT));
231    Symbol->setBinding(ELF::STB_GNU_UNIQUE);
232    Symbol->setExternal(true);
233    break;
234
235  case MCSA_Global:
236    Symbol->setBinding(ELF::STB_GLOBAL);
237    Symbol->setExternal(true);
238    break;
239
240  case MCSA_WeakReference:
241  case MCSA_Weak:
242    Symbol->setBinding(ELF::STB_WEAK);
243    Symbol->setExternal(true);
244    break;
245
246  case MCSA_Local:
247    Symbol->setBinding(ELF::STB_LOCAL);
248    Symbol->setExternal(false);
249    break;
250
251  case MCSA_ELF_TypeFunction:
252    Symbol->setType(CombineSymbolTypes(Symbol->getType(), ELF::STT_FUNC));
253    break;
254
255  case MCSA_ELF_TypeIndFunction:
256    Symbol->setType(CombineSymbolTypes(Symbol->getType(), ELF::STT_GNU_IFUNC));
257    break;
258
259  case MCSA_ELF_TypeObject:
260    Symbol->setType(CombineSymbolTypes(Symbol->getType(), ELF::STT_OBJECT));
261    break;
262
263  case MCSA_ELF_TypeTLS:
264    Symbol->setType(CombineSymbolTypes(Symbol->getType(), ELF::STT_TLS));
265    break;
266
267  case MCSA_ELF_TypeCommon:
268    // TODO: Emit these as a common symbol.
269    Symbol->setType(CombineSymbolTypes(Symbol->getType(), ELF::STT_OBJECT));
270    break;
271
272  case MCSA_ELF_TypeNoType:
273    Symbol->setType(CombineSymbolTypes(Symbol->getType(), ELF::STT_NOTYPE));
274    break;
275
276  case MCSA_Protected:
277    Symbol->setVisibility(ELF::STV_PROTECTED);
278    break;
279
280  case MCSA_Hidden:
281    Symbol->setVisibility(ELF::STV_HIDDEN);
282    break;
283
284  case MCSA_Internal:
285    Symbol->setVisibility(ELF::STV_INTERNAL);
286    break;
287
288  case MCSA_AltEntry:
289    llvm_unreachable("ELF doesn't support the .alt_entry attribute");
290  }
291
292  return true;
293}
294
295void MCELFStreamer::EmitCommonSymbol(MCSymbol *S, uint64_t Size,
296                                     unsigned ByteAlignment) {
297  auto *Symbol = cast<MCSymbolELF>(S);
298  getAssembler().registerSymbol(*Symbol);
299
300  if (!Symbol->isBindingSet()) {
301    Symbol->setBinding(ELF::STB_GLOBAL);
302    Symbol->setExternal(true);
303  }
304
305  Symbol->setType(ELF::STT_OBJECT);
306
307  if (Symbol->getBinding() == ELF::STB_LOCAL) {
308    MCSection &Section = *getAssembler().getContext().getELFSection(
309        ".bss", ELF::SHT_NOBITS, ELF::SHF_WRITE | ELF::SHF_ALLOC);
310    MCSectionSubPair P = getCurrentSection();
311    SwitchSection(&Section);
312
313    EmitValueToAlignment(ByteAlignment, 0, 1, 0);
314    EmitLabel(Symbol);
315    EmitZeros(Size);
316
317    // Update the maximum alignment of the section if necessary.
318    if (ByteAlignment > Section.getAlignment())
319      Section.setAlignment(ByteAlignment);
320
321    SwitchSection(P.first, P.second);
322  } else {
323    if(Symbol->declareCommon(Size, ByteAlignment))
324      report_fatal_error("Symbol: " + Symbol->getName() +
325                         " redeclared as different type");
326  }
327
328  cast<MCSymbolELF>(Symbol)
329      ->setSize(MCConstantExpr::create(Size, getContext()));
330}
331
332void MCELFStreamer::emitELFSize(MCSymbolELF *Symbol, const MCExpr *Value) {
333  Symbol->setSize(Value);
334}
335
336void MCELFStreamer::EmitLocalCommonSymbol(MCSymbol *S, uint64_t Size,
337                                          unsigned ByteAlignment) {
338  auto *Symbol = cast<MCSymbolELF>(S);
339  // FIXME: Should this be caught and done earlier?
340  getAssembler().registerSymbol(*Symbol);
341  Symbol->setBinding(ELF::STB_LOCAL);
342  Symbol->setExternal(false);
343  EmitCommonSymbol(Symbol, Size, ByteAlignment);
344}
345
346void MCELFStreamer::EmitValueImpl(const MCExpr *Value, unsigned Size,
347                                  SMLoc Loc) {
348  if (isBundleLocked())
349    report_fatal_error("Emitting values inside a locked bundle is forbidden");
350  fixSymbolsInTLSFixups(Value);
351  MCObjectStreamer::EmitValueImpl(Value, Size, Loc);
352}
353
354void MCELFStreamer::EmitValueToAlignment(unsigned ByteAlignment,
355                                         int64_t Value,
356                                         unsigned ValueSize,
357                                         unsigned MaxBytesToEmit) {
358  if (isBundleLocked())
359    report_fatal_error("Emitting values inside a locked bundle is forbidden");
360  MCObjectStreamer::EmitValueToAlignment(ByteAlignment, Value,
361                                         ValueSize, MaxBytesToEmit);
362}
363
364// Add a symbol for the file name of this module. They start after the
365// null symbol and don't count as normal symbol, i.e. a non-STT_FILE symbol
366// with the same name may appear.
367void MCELFStreamer::EmitFileDirective(StringRef Filename) {
368  getAssembler().addFileName(Filename);
369}
370
371void MCELFStreamer::EmitIdent(StringRef IdentString) {
372  MCSection *Comment = getAssembler().getContext().getELFSection(
373      ".comment", ELF::SHT_PROGBITS, ELF::SHF_MERGE | ELF::SHF_STRINGS, 1, "");
374  PushSection();
375  SwitchSection(Comment);
376  if (!SeenIdent) {
377    EmitIntValue(0, 1);
378    SeenIdent = true;
379  }
380  EmitBytes(IdentString);
381  EmitIntValue(0, 1);
382  PopSection();
383}
384
385void MCELFStreamer::fixSymbolsInTLSFixups(const MCExpr *expr) {
386  switch (expr->getKind()) {
387  case MCExpr::Target:
388    cast<MCTargetExpr>(expr)->fixELFSymbolsInTLSFixups(getAssembler());
389    break;
390  case MCExpr::Constant:
391    break;
392
393  case MCExpr::Binary: {
394    const MCBinaryExpr *be = cast<MCBinaryExpr>(expr);
395    fixSymbolsInTLSFixups(be->getLHS());
396    fixSymbolsInTLSFixups(be->getRHS());
397    break;
398  }
399
400  case MCExpr::SymbolRef: {
401    const MCSymbolRefExpr &symRef = *cast<MCSymbolRefExpr>(expr);
402    switch (symRef.getKind()) {
403    default:
404      return;
405    case MCSymbolRefExpr::VK_GOTTPOFF:
406    case MCSymbolRefExpr::VK_INDNTPOFF:
407    case MCSymbolRefExpr::VK_NTPOFF:
408    case MCSymbolRefExpr::VK_GOTNTPOFF:
409    case MCSymbolRefExpr::VK_TLSGD:
410    case MCSymbolRefExpr::VK_TLSLD:
411    case MCSymbolRefExpr::VK_TLSLDM:
412    case MCSymbolRefExpr::VK_TPOFF:
413    case MCSymbolRefExpr::VK_TPREL:
414    case MCSymbolRefExpr::VK_DTPOFF:
415    case MCSymbolRefExpr::VK_DTPREL:
416    case MCSymbolRefExpr::VK_PPC_DTPMOD:
417    case MCSymbolRefExpr::VK_PPC_TPREL_LO:
418    case MCSymbolRefExpr::VK_PPC_TPREL_HI:
419    case MCSymbolRefExpr::VK_PPC_TPREL_HA:
420    case MCSymbolRefExpr::VK_PPC_TPREL_HIGHER:
421    case MCSymbolRefExpr::VK_PPC_TPREL_HIGHERA:
422    case MCSymbolRefExpr::VK_PPC_TPREL_HIGHEST:
423    case MCSymbolRefExpr::VK_PPC_TPREL_HIGHESTA:
424    case MCSymbolRefExpr::VK_PPC_DTPREL_LO:
425    case MCSymbolRefExpr::VK_PPC_DTPREL_HI:
426    case MCSymbolRefExpr::VK_PPC_DTPREL_HA:
427    case MCSymbolRefExpr::VK_PPC_DTPREL_HIGHER:
428    case MCSymbolRefExpr::VK_PPC_DTPREL_HIGHERA:
429    case MCSymbolRefExpr::VK_PPC_DTPREL_HIGHEST:
430    case MCSymbolRefExpr::VK_PPC_DTPREL_HIGHESTA:
431    case MCSymbolRefExpr::VK_PPC_GOT_TPREL:
432    case MCSymbolRefExpr::VK_PPC_GOT_TPREL_LO:
433    case MCSymbolRefExpr::VK_PPC_GOT_TPREL_HI:
434    case MCSymbolRefExpr::VK_PPC_GOT_TPREL_HA:
435    case MCSymbolRefExpr::VK_PPC_GOT_DTPREL:
436    case MCSymbolRefExpr::VK_PPC_GOT_DTPREL_LO:
437    case MCSymbolRefExpr::VK_PPC_GOT_DTPREL_HI:
438    case MCSymbolRefExpr::VK_PPC_GOT_DTPREL_HA:
439    case MCSymbolRefExpr::VK_PPC_TLS:
440    case MCSymbolRefExpr::VK_PPC_GOT_TLSGD:
441    case MCSymbolRefExpr::VK_PPC_GOT_TLSGD_LO:
442    case MCSymbolRefExpr::VK_PPC_GOT_TLSGD_HI:
443    case MCSymbolRefExpr::VK_PPC_GOT_TLSGD_HA:
444    case MCSymbolRefExpr::VK_PPC_TLSGD:
445    case MCSymbolRefExpr::VK_PPC_GOT_TLSLD:
446    case MCSymbolRefExpr::VK_PPC_GOT_TLSLD_LO:
447    case MCSymbolRefExpr::VK_PPC_GOT_TLSLD_HI:
448    case MCSymbolRefExpr::VK_PPC_GOT_TLSLD_HA:
449    case MCSymbolRefExpr::VK_PPC_TLSLD:
450      break;
451    }
452    getAssembler().registerSymbol(symRef.getSymbol());
453    cast<MCSymbolELF>(symRef.getSymbol()).setType(ELF::STT_TLS);
454    break;
455  }
456
457  case MCExpr::Unary:
458    fixSymbolsInTLSFixups(cast<MCUnaryExpr>(expr)->getSubExpr());
459    break;
460  }
461}
462
463void MCELFStreamer::EmitInstToFragment(const MCInst &Inst,
464                                       const MCSubtargetInfo &STI) {
465  this->MCObjectStreamer::EmitInstToFragment(Inst, STI);
466  MCRelaxableFragment &F = *cast<MCRelaxableFragment>(getCurrentFragment());
467
468  for (unsigned i = 0, e = F.getFixups().size(); i != e; ++i)
469    fixSymbolsInTLSFixups(F.getFixups()[i].getValue());
470}
471
472void MCELFStreamer::EmitInstToData(const MCInst &Inst,
473                                   const MCSubtargetInfo &STI) {
474  MCAssembler &Assembler = getAssembler();
475  SmallVector<MCFixup, 4> Fixups;
476  SmallString<256> Code;
477  raw_svector_ostream VecOS(Code);
478  Assembler.getEmitter().encodeInstruction(Inst, VecOS, Fixups, STI);
479
480  for (unsigned i = 0, e = Fixups.size(); i != e; ++i)
481    fixSymbolsInTLSFixups(Fixups[i].getValue());
482
483  // There are several possibilities here:
484  //
485  // If bundling is disabled, append the encoded instruction to the current data
486  // fragment (or create a new such fragment if the current fragment is not a
487  // data fragment).
488  //
489  // If bundling is enabled:
490  // - If we're not in a bundle-locked group, emit the instruction into a
491  //   fragment of its own. If there are no fixups registered for the
492  //   instruction, emit a MCCompactEncodedInstFragment. Otherwise, emit a
493  //   MCDataFragment.
494  // - If we're in a bundle-locked group, append the instruction to the current
495  //   data fragment because we want all the instructions in a group to get into
496  //   the same fragment. Be careful not to do that for the first instruction in
497  //   the group, though.
498  MCDataFragment *DF;
499
500  if (Assembler.isBundlingEnabled()) {
501    MCSection &Sec = *getCurrentSectionOnly();
502    if (Assembler.getRelaxAll() && isBundleLocked())
503      // If the -mc-relax-all flag is used and we are bundle-locked, we re-use
504      // the current bundle group.
505      DF = BundleGroups.back();
506    else if (Assembler.getRelaxAll() && !isBundleLocked())
507      // When not in a bundle-locked group and the -mc-relax-all flag is used,
508      // we create a new temporary fragment which will be later merged into
509      // the current fragment.
510      DF = new MCDataFragment();
511    else if (isBundleLocked() && !Sec.isBundleGroupBeforeFirstInst())
512      // If we are bundle-locked, we re-use the current fragment.
513      // The bundle-locking directive ensures this is a new data fragment.
514      DF = cast<MCDataFragment>(getCurrentFragment());
515    else if (!isBundleLocked() && Fixups.size() == 0) {
516      // Optimize memory usage by emitting the instruction to a
517      // MCCompactEncodedInstFragment when not in a bundle-locked group and
518      // there are no fixups registered.
519      MCCompactEncodedInstFragment *CEIF = new MCCompactEncodedInstFragment();
520      insert(CEIF);
521      CEIF->getContents().append(Code.begin(), Code.end());
522      return;
523    } else {
524      DF = new MCDataFragment();
525      insert(DF);
526    }
527    if (Sec.getBundleLockState() == MCSection::BundleLockedAlignToEnd) {
528      // If this fragment is for a group marked "align_to_end", set a flag
529      // in the fragment. This can happen after the fragment has already been
530      // created if there are nested bundle_align groups and an inner one
531      // is the one marked align_to_end.
532      DF->setAlignToBundleEnd(true);
533    }
534
535    // We're now emitting an instruction in a bundle group, so this flag has
536    // to be turned off.
537    Sec.setBundleGroupBeforeFirstInst(false);
538  } else {
539    DF = getOrCreateDataFragment();
540  }
541
542  // Add the fixups and data.
543  for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
544    Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
545    DF->getFixups().push_back(Fixups[i]);
546  }
547  DF->setHasInstructions(true);
548  DF->getContents().append(Code.begin(), Code.end());
549
550  if (Assembler.isBundlingEnabled() && Assembler.getRelaxAll()) {
551    if (!isBundleLocked()) {
552      mergeFragment(getOrCreateDataFragment(), DF);
553      delete DF;
554    }
555  }
556}
557
558void MCELFStreamer::EmitBundleAlignMode(unsigned AlignPow2) {
559  assert(AlignPow2 <= 30 && "Invalid bundle alignment");
560  MCAssembler &Assembler = getAssembler();
561  if (AlignPow2 > 0 && (Assembler.getBundleAlignSize() == 0 ||
562                        Assembler.getBundleAlignSize() == 1U << AlignPow2))
563    Assembler.setBundleAlignSize(1U << AlignPow2);
564  else
565    report_fatal_error(".bundle_align_mode cannot be changed once set");
566}
567
568void MCELFStreamer::EmitBundleLock(bool AlignToEnd) {
569  MCSection &Sec = *getCurrentSectionOnly();
570
571  // Sanity checks
572  //
573  if (!getAssembler().isBundlingEnabled())
574    report_fatal_error(".bundle_lock forbidden when bundling is disabled");
575
576  if (!isBundleLocked())
577    Sec.setBundleGroupBeforeFirstInst(true);
578
579  if (getAssembler().getRelaxAll() && !isBundleLocked()) {
580    // TODO: drop the lock state and set directly in the fragment
581    MCDataFragment *DF = new MCDataFragment();
582    BundleGroups.push_back(DF);
583  }
584
585  Sec.setBundleLockState(AlignToEnd ? MCSection::BundleLockedAlignToEnd
586                                    : MCSection::BundleLocked);
587}
588
589void MCELFStreamer::EmitBundleUnlock() {
590  MCSection &Sec = *getCurrentSectionOnly();
591
592  // Sanity checks
593  if (!getAssembler().isBundlingEnabled())
594    report_fatal_error(".bundle_unlock forbidden when bundling is disabled");
595  else if (!isBundleLocked())
596    report_fatal_error(".bundle_unlock without matching lock");
597  else if (Sec.isBundleGroupBeforeFirstInst())
598    report_fatal_error("Empty bundle-locked group is forbidden");
599
600  // When the -mc-relax-all flag is used, we emit instructions to fragments
601  // stored on a stack. When the bundle unlock is emitted, we pop a fragment
602  // from the stack a merge it to the one below.
603  if (getAssembler().getRelaxAll()) {
604    assert(!BundleGroups.empty() && "There are no bundle groups");
605    MCDataFragment *DF = BundleGroups.back();
606
607    // FIXME: Use BundleGroups to track the lock state instead.
608    Sec.setBundleLockState(MCSection::NotBundleLocked);
609
610    // FIXME: Use more separate fragments for nested groups.
611    if (!isBundleLocked()) {
612      mergeFragment(getOrCreateDataFragment(), DF);
613      BundleGroups.pop_back();
614      delete DF;
615    }
616
617    if (Sec.getBundleLockState() != MCSection::BundleLockedAlignToEnd)
618      getOrCreateDataFragment()->setAlignToBundleEnd(false);
619  } else
620    Sec.setBundleLockState(MCSection::NotBundleLocked);
621}
622
623void MCELFStreamer::FinishImpl() {
624  // Ensure the last section gets aligned if necessary.
625  MCSection *CurSection = getCurrentSectionOnly();
626  setSectionAlignmentForBundling(getAssembler(), CurSection);
627
628  EmitFrames(nullptr);
629
630  this->MCObjectStreamer::FinishImpl();
631}
632
633MCStreamer *llvm::createELFStreamer(MCContext &Context, MCAsmBackend &MAB,
634                                    raw_pwrite_stream &OS, MCCodeEmitter *CE,
635                                    bool RelaxAll) {
636  MCELFStreamer *S = new MCELFStreamer(Context, MAB, OS, CE);
637  if (RelaxAll)
638    S->getAssembler().setRelaxAll(true);
639  return S;
640}
641
642void MCELFStreamer::EmitThumbFunc(MCSymbol *Func) {
643  llvm_unreachable("Generic ELF doesn't support this directive");
644}
645
646void MCELFStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
647  llvm_unreachable("ELF doesn't support this directive");
648}
649
650void MCELFStreamer::BeginCOFFSymbolDef(const MCSymbol *Symbol) {
651  llvm_unreachable("ELF doesn't support this directive");
652}
653
654void MCELFStreamer::EmitCOFFSymbolStorageClass(int StorageClass) {
655  llvm_unreachable("ELF doesn't support this directive");
656}
657
658void MCELFStreamer::EmitCOFFSymbolType(int Type) {
659  llvm_unreachable("ELF doesn't support this directive");
660}
661
662void MCELFStreamer::EndCOFFSymbolDef() {
663  llvm_unreachable("ELF doesn't support this directive");
664}
665
666void MCELFStreamer::EmitZerofill(MCSection *Section, MCSymbol *Symbol,
667                                 uint64_t Size, unsigned ByteAlignment) {
668  llvm_unreachable("ELF doesn't support this directive");
669}
670
671void MCELFStreamer::EmitTBSSSymbol(MCSection *Section, MCSymbol *Symbol,
672                                   uint64_t Size, unsigned ByteAlignment) {
673  llvm_unreachable("ELF doesn't support this directive");
674}
675